Transmission diamond imaging detector

At a Glance

Metadata	Details
Publication Date	2016-01-01
Journal	AIP conference proceedings
Authors	J. Smedley, Erik Müller, D. Pinelli, Wenxiang Ding, Mengjia Gaoweia
Institutions	Stony Brook University, Case Western Reserve University
Analysis	Full AI Review Included

Technical Documentation & Analysis: Transmission Diamond Imaging Detector

6CCVD Analysis of AIP Conf. Proc. 1741, 040006 (2016)

This document analyzes the requirements and achievements detailed in the research paper “Transmission diamond imaging detector” and maps them directly to the advanced material and fabrication capabilities offered by 6CCVD.

Executive Summary

The development of a high-performance, transmission-mode X-ray imaging detector utilizing MPCVD Single Crystal Diamond (SCD) represents a significant advance in synchrotron beam diagnostics.

Core Achievement: Demonstration of a 1-kilopixel (32x32) transmission detector capable of real-time (32 Hz video rate) imaging of high-flux X-ray beams.
Material Selection: The use of ultra-low nitrogen (ULN) Single Crystal Diamond (SCD) ensures minimal X-ray absorption and superior thermal management, critical for high-flux environments.
High Resolution: The device features a 60 µm pixel pitch, providing detailed beam morphology, flux, and position information non-destructively.
Exceptional Dynamic Range: Confirmed operation across a dynamic range exceeding 7 orders of magnitude (10⁷ to 10¹⁴ absorbed photons/s at 10 keV).
Advanced Fabrication: Successful integration required precision thinning (50 µm), custom lithography (Pt contacts), and high-reliability brazing (TiCuSil eutectic) onto a Polycrystalline Diamond (PCD) support window.
Application Impact: This technology is designed to replace traditional beryllium windows, serving as the instrumented vacuum-air interface for the XFP beamline at NSLS-II.

Technical Specifications

The following hard data points were extracted from the research paper detailing the detector design and performance.

Parameter	Value	Unit	Context
Diamond Material Grade	Single Crystal Diamond (SCD)	N/A	Ultra-low nitrogen (ULN), IIa
Crystal Orientation	[100]	N/A	Surface growth/processing orientation
Detector Dimensions	4.7 x 4.7	mm²	Active SCD plate size
Detector Thickness	50	µm	Precision laser cut and polished
Pixel Array Size	32 x 32	Pixels	Total 1 kilopixel detector
Pixel Pitch	60	µm	Defined by 45 µm strips + 15 µm spacing
Electrode Material	Platinum (Pt)	N/A	25 nm thickness, sputter-coated
Bias Voltage (V_bias)	~40	V	Required for full carrier collection
Maximum Switching Rate	1	kHz	Bias cycling rate
Image Frame Rate	32	Hz	Full image video readout rate
Dynamic Range	> 7	Orders of Magnitude	Flux range capability
Current Readout Range	20 nA to 140 mA	N/A	Corresponds to 10⁷ to 10¹⁴ absorbed photons/s (10 keV)

Key Methodologies

The fabrication of this high-performance transmission detector required stringent control over material properties, surface preparation, and micro-patterning.

Material Selection and Screening: Ultra-low nitrogen SCD was selected for its intrinsic semiconductor properties and low absorption. Plates were screened via optical birefringence to identify and reject potential electrically active defects.
Precision Thinning: The SCD plate was laser cut and polished to a final thickness of 50 µm.
Surface Termination: Polished diamond plates were cleaned and exposed to a UV-lamp in air for four hours per side, resulting in oxygen termination to minimize the impact of defects by maintaining a high Schottky barrier.
Lithography: Standard photolithography procedures were used to define the 32-stripe pattern:
- Photoresist (Microposit S1805) spun at 6000 rpm.
- Baked at 100 °C for 3 minutes.
- UV exposure for 12 seconds.
- Developed in Microposit MF312 solution.
Metalization and Lift-off: 25 nm thick Platinum (Pt) contacts were sputter-coated onto the surface, followed by lift-off in acetone to define the electrode pattern (45 µm strips, 15 µm spacing). The process was repeated on the opposite face, rotated 90°.
Brazing and Integration: The patterned SCD was brazed to a 13 mm diameter Polycrystalline Diamond (PCD) window using a Titanium-Copper-Silver (TiCuSil) eutectic braze joint, ensuring mechanical stability and thermal coupling.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the advanced MPCVD diamond materials and precision fabrication services required to replicate, scale, and extend this critical synchrotron diagnostic technology.

Applicable Materials

To achieve the high-transmission, high-purity performance demonstrated in this paper, 6CCVD recommends the following materials:

Optical Grade Single Crystal Diamond (SCD): Essential for X-ray transmission detectors. Our SCD is grown with ultra-low nitrogen (ULN) content, ensuring minimal absorption and maximizing charge collection efficiency under high-flux conditions.
Polycrystalline Diamond (PCD) Substrates: Recommended for the intermediate support window, providing mechanical strength and superior thermal conductivity for the brazing process, especially for large-area detectors. 6CCVD can supply PCD plates up to 125 mm in diameter.

Customization Potential

The success of this detector hinges on precise dimensional control and specialized surface engineering—all core capabilities of 6CCVD.

Requirement from Paper	6CCVD Capability	Technical Advantage
50 µm Thickness	SCD plates available from 0.1 µm to 500 µm.	Guaranteed thickness uniformity and high-precision laser cutting for custom geometries (e.g., 4.7x4.7 mm²).
Ultra-Smooth Surface	SCD Polishing: Ra < 1 nm.	Minimizes surface defects that can impact lithography yield and electrical performance (Schottky barrier uniformity).
Platinum (Pt) Contacts	Full internal metalization capability.	We offer custom deposition of Pt, Ti/Pt/Au, W, Cu, or other stacks required for specific contact schemes and brazing compatibility.
PCD Support Window	Custom PCD plates up to 125 mm diameter.	Supply of the brazing substrate, including precision laser cutting of internal apertures (e.g., 3.4x3.4 mm² hole) for transmission path.
Global Logistics	Global shipping (DDU default, DDP available).	Reliable, insured delivery of sensitive, high-value diamond components worldwide.

Engineering Support

The development of advanced X-ray detectors requires deep expertise in material science, radiation physics, and surface chemistry.

Material Selection for Harsh Environments: 6CCVD’s in-house PhD team specializes in assisting engineers with material selection for similar Synchrotron Beam Monitoring and High-Flux X-ray Detection projects, focusing on radiation hardness and thermal management.
Metalization Optimization: We provide consultation on optimizing metalization schemes (e.g., Ti/Pt/Au stacks) to ensure robust ohmic or Schottky contacts, crucial for high-speed switching and reliable wirebonding, as required by the 32x32 pixel architecture.
Surface Preparation: We can provide diamond plates with specific surface terminations (e.g., oxygen termination via UV/O₂ cleaning) to enhance device performance and minimize the impact of electrically active defects, replicating the methodology used in this research.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Many modern synchrotron techniques are trending toward use of high flux beams and/or beams which require enhanced stability and precise understanding of beam position and intensity from the front end of the beamline all the way to the sample. For high flux beams, major challenges include heat load management in optics (including the vacuum windows) and a mechanism of real-time volumetric measurement of beam properties such as flux, position, and morphology. For beam stability in these environments, feedback from such measurements directly to control systems for optical elements or to sample positioning stages would be invaluable. To address these challenges, we are developing diamond-based instrumented vacuum windows with integrated volumetric x-ray intensity, beam profile and beam-position monitoring capabilities. A 50 µm thick single crystal diamond has been lithographically patterned to produce 60 µm pixels, creating a >1kilopixel free-standing transmission imaging detector. This device, coupled with a custom, FPGA-based readout, has been used to image both white and monochromatic x-ray beams and capture the last x-ray photons at the National Synchrotron Light Source (NSLS). This technology will form the basis for the instrumented end-station window of the x-ray footprinting beamline (XFP) at NSLS-II.

Tech Support

Original Source

DOI: https://doi.org/10.1063/1.4952878